C# 4 and .NET 4

1112 ❘ ChaPTer 38 silverliGht
javascript Calling silverlight
To make a .NET method available from JavaScript, the attribute ScriptableMember must be applied.
If you would like to make all members of a class available from JavaScript, you can apply the attribute
ScriptableType instead. Here, the attribute ScriptableMember is applied to the method ToUpper(),
which changes the input string to uppercase.
[ScriptableMember]
public string ToUpper(string s)
{
return s.ToUpper();
}
code snippet JavaScriptInterop/MainPage.xaml.cs
The type containing scriptable members must be registered with the HTML page so that it can be found by
scripting. This is done by invoking the RegisterScriptableObject() method from the HtmlPage class.
The first argument of this method is a key name that is used by JavaScript to find the object. The second
argument defines the instance that is used to access the scriptable members.
public MainPage()
{
InitializeComponent();
//...
}
HtmlPage.RegisterScriptableObject("ScriptKey", this);
Now it is possible to access the .NET code from JavaScript. To find the scriptable object from JavaScript,
the Silverlight control must be accessed. To make this easier, an id attribute is added to the object tag that
references the Silverlight package. Also, text and button elements are added to the HTML code. The button
has the JavaScript function callDotnet() assigned to the onclick event where the call to managed
code happens.
code snippet SilverlightDemos.Web/JavaScripInteropTestPage.html
The JavaScript function callDotnet() uses the plugin identifier to find the Silverlight control with
getElementById(). By using the ScriptKey defined earlier with the registration, the scriptable type can
now be accessed. Using this scriptable type, the method ToUpper() is now available to change the input
to uppercase.
function callDotnet() {
var plugin = document.getElementById("plugin");
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